The invention relates to a reflex photometric assembly for a camera, and more particularly, to a photometric assembly for use in a camera of the reflective photometric type in which light from an object being photographed which passes through a taking lens is reflected by a film surface or the surface of a shutter blind of a focal plane shutter and is guided by a reflecting member to impinge on a photoelectric transducer element which is provided for the purpose of photometry.
In a single lens reflex camera utilizing a focal plane shutter, a reflex photometric assembly has already been proposed in which a reflecting member is utilized to direct light reflected from the surface of a first shutter blind or a film surface exposed by running of the blind to a photoelectric transducer element which is disposed in the bottom of a dark box and a proper exposure is provided by controlling the amount of light received by the transducer element. In such an assembly, the transducer element for photometry and an IC package forming an exposure control circuit can be formed as one integral package which may be directly disposed on a printed circuit board. This avoids the need to route a signal current from the transducer element which has a minimal magnitude to spaced or remote points, thus eliminating the likelihood of malfunctioning in response to extraneous noises or a discontinuity in the lead wires. The incorporation of the transducer element and the IC package into an integral unit reduces the cost and the space requirement, affording the advantage of allowing effective utilization of the available space.
However, a point with this assembly is the fact that only the light which is reflected by the reflecting member must be directed to impinge on the transducer element. If the light reflected by the blind surface or the film surface directly impinges on the transducer element if the proportion is small, the distribution of light receiving sensitivity is disturbed, preventing an accurate photometry. Consequently, it is necessary to provide a shield member or members which prevent a direct impingement of the reflected light from the blind or the film surface onto the transducer element.
However, when shielding the reflected light from the film surface which directly impinges on the transducer element, the impingement of the light from the reflecting member onto the transducer element must not be intercepted or otherwise an accurate photometry is again prevented. In addition, the provision of the shield member involves the likelihood that a reduced magnitude of a photometric output may degrade the performance of an associated camera. Hence, the location of the shield member is extremely delicate which reliable prevents the direct impingement of the light reflected from the blind or the film surface without intercepting the incident light from the reflecting member. It is difficult to attain a desired effect as described above only by securing the shield member to a fixed member.
Therefore, the inventor has previously proposed a reflex photometric assembly which includes an adjustable shield member covering the light receiving surface of a photoelectric transducer element so as to prevent a direct impingement of the reflected light from the blind or the film surface without intercepting the incident light upon the photoelectric transducer element from a reflecting member (U.S. application Ser. No. 253,722).
However, the proposed photometric assembly needs the delicate adjustment for securing the shield member in a proper shielding position and hence is inadequate for introducing it into the assembling process aiming at the recent automation developments in.